java classes for xml schema

Hi, Please suggest the best practices of creating java classes for xml schema (.xsd). Actually the requirement is to instantiate java objects, payment details and eventually send an xml file with details of shooping cart to payment gateway. In have some understanding about JAXB that I had used earlier for capturing of census data from remote locations.

Thanks for your input. I have just begun with Castor. Though I stumbled initally while creating java classes with the existing .xsd file because of some Special Data Type like GUID with curly braces, yet I still continued with it. I found it limiting at times when schema had special elements of data type.

Do you think I still might consider moving over to jaxb considering the problems I had initially. Pl. consider that my requirement is to create xml file(input) from shopping cart and create output as xml to be passed it over to payment gateway.